Porous gas diffusion elements are well known to those skilled in the art. Thus, for example, they are disclosed in U.S. Pat. Nos. 4,261,932, 4,261,933, and 4,288,935; the disclosure of each of these patents is hereby incorporated by reference into this specification.
These prior art porous gas diffusers are often used to diffuse a gas (such as oxygen, ozone, air, carbon dioxide, or nitrogen) into a liquid (such as waste water or drinking water). An ASCE Standard Test ("Measurement of Oxygen Transfer in Clean Water," Jul., 1984, ISBN 0-87262-430-7) was developed by the American Society of Civil Engineers to evaluate the efficiencies of these prior art devices.
A substantial amount of energy is required to force gas through such porous gas diffusers. The efficiencies of the prior art gas diffusion devices ranged from about 10 to about 40 percent. Thus, even a relatively small increase in such efficiency will result in a significant decrease in energy consumption.
It is an object of this invention to provide a porous gas diffuser with an increased gas transfer efficiency.
It is yet another object of this invention to provide a porous gas diffuser whose output is substantially uniform along its active surface.
It is yet another object of this invention to provide a porous gas diffuser which, when connected a source of gas, is less likely to leak such gas from a source other than the active surface of the diffuser.